Process for the preparation of sweet high octane gasoline



Patented Feb. 13, 1945' V poration oi Delaware No Drawing.

PROCESS roeene PREPARATION swns'r n on OCTANE GASOLINE H Herbert G. -M.,=Fischer, Westfield, N. .L, assignor to Standard Oil Develop rrient Company, a; cor

Application September 4, 1941, Serial 100,409,489

H 1 5' l ims, (01. 196--33)" The present "invention relates to the art ofrefining hydrocarbon oils. As is generally known,

a-number of} hydrocarbonoils such as gasoline,

naphthas'and gas oil contain sulfur 'in* various forms. For example, most of the gasolinesfproduced in this country, in the raw state, contain appreciable amounts for hydrogen sulfide, thicphenes, and-mercaptans; "The presence of these compounds in commercial petroleum products is V objectionable due totheir offensive orsour" odor and, consequently, most refineries sweeten these products beforerelease to the trade.

An ordinary-method of sweetening sour hydrocarbon-oils: is totreat them by the so-called I lead doctor method. Briefly, thisprocessi consists of treating the sour hydrocarbon oil wane sodium plumbitesolution or; many. event; 'an aqueous medium containing dissolved lead oxide and sodium hydroxide. Prior to this treatment, however; the more easily removable sulfurcompoundsAsuch as 'HzSf are removed by simple treatment withsodium carbonate solution, caustic soda, or the like. This preliminary treatment, however, fails to IEmGV G' substantial amounts of merc'aptanss Iti'nay be=said= that the treatment of gasoline or other'hydrocarbon oil with the lead doctor I solution does notgenerally remove the mercaptans contained in the gasoline but converts: them by oxidation to a form inwhich they 'areless odor-iferous and objectionable, 1 The exact mechanism of the reaction" is a subject'of-some I dispute, but a working hypothesis, at least, of

thereaction which takesplace when sour gasoline containing mercaptans is treated 'with' lead doctor solution is the explanation that lead mercaptides are'first formed by interaction betweenthe mercaptans and the sodium plumbite, followed by careful addition of sulfur, whereupon the mercaptides and the sulfur react to form lead sulfide which precipitates from the gasoline and organic disulfides. In other words, the mercaptan is oxidized to the corresponding and less objectionable disulfide. f

Inthe sulfur addition previously referred to, emulsiflcation frequently occurs, that is to say,

sodium plumbite is further teated with sulfur, an emulsion containing gasoline forms at the bot"- tom of the treatingzorreas a distinct phase from the upper sweetenfid gasoline phase. The phases are separated byany conventionalmethod such as decantation and the emulsion is frequently centrifuged in the sweetening plant to separate the components, and samples of naphtha recovered from such a process showed the following analysis: g

Y l irstjsamplei h l Second sample,

, Rerun asreceived Asrcceived to-98%' overhead Sulfur, per cen,t 30.895 0. 643 0.600 Color l0 Tag Robin- +188 10% Tag Robson; inson. Reactive. sulfur, mgl 13 100 ml. p Octane number; A. 52.4 68.2 54.3

. M.clear.

oted, that the above s n or naphthais or conspicuously poor quality, so that if it is added,after recovery from the centrifuging operation, to theremainder of the gasoline, the'gfinal' product is degraded accordingly.

*lihav'e now foundthat thenaphtha or gasoline recovered from the aforesaid centrifuging oper- 'atiorrcan be improved as to quality by a reformi-ng b'peration The main object of the present invention, therefore, is to improve the quality of a hydrocarbon oil recovered from the emulsified portion of a doctor sweetening operation, particularly as to octane number and sulfur content, by a thermal or catalytic reforming operation.

In carrying my invention into effect, and particularly to show the utility thereof, the second sample specification above was heated to 1000 F.

' under a pressure of 500 lbs/sq. in. and passed through a reaction chamber at a space velocity of 6 volumes of oil per volume of chamber per .When mefg solm which has, b en treated with v redistilled to recover a product having a 400 end point and a Reid vapor pressure of 10 lbs.

Complete inspection of the original and reformed products are contained in the table below:

N aphtha L 1: 1 R i d aug in e orme Stock and procedure centrifuge product (as received) Operating conditions:

Temperature F.. 1,000 Pressure .#/sq. in.. 500 Feed rate -.v./v./hr-. 6 Gasoline inspections:

olor, Tag. Rob 10% Color, Saybolt +10 Doctor test Mg. reactive 3/100 ml. Trace Sulfur .Wt. per ce t-- 0.119 Octane No.:

A. S. T. M.clear 54. 3 79. 7 A S. T. M.+l% ml lead/gal 60. 4 82. 5 C. F. R. R.-clear 61. 5 92. 2 C. F. R.+l% ml. tetraethyl lead/gal 65. 1 95. 3 Reid vapor pressure.- ..#/sq. 1.11.- 9. 4 Gravit P. 1.. 50. 5 47. 4 Distillation of naphtha:

I. B. P 156 121 Per cent tit- 158 F 6. 0 212 F- 7. 0 81. 0 257 F. 28. 5 51.0 302 F. 57. 0 74. 5 356 F..-- 86. 0 91. 5 392 96. 0 97. 0 F. B. P-..- 411 405 Per cent recover 98.0 (is. 5 Per cent less 0. 9 l). 2 Dry gas analysis 5 from reforming operation:

Hydrogen volume per cent. 7. 0 Methane- 35. 0 Ethane 24. 7 Ethylene. 5. l Propane 0.... l6. 7 Propylene 1o..-- l1. 5

1 Passed. 1 Did not pass.

3 Corrected to 02, Hz, 00 free basis.

By performing the operation, it will be noted that the sulfur content was reduced from 0.6 to 0.119%, and that the octane number was in-- creased from 54.3 to 79.7 (American Society for Temperature 900-1050 F. Pressure 2004.000 lbs. Feed rate 5-15 volumes of oil per volume of reaction space per hour To recapitulate, the present invention relates to improvements in the treatment of gasoline,

naphthas, or any other hydrocarbon oil which has been sweetened by the usual lead doctor method. As is known, following the addition of sulfur in this operation, the sweetened mixture is settled and an emulsion phase is formed at the oil-doctor solution interface. This emulsion may contain from 5% to of hydrocarbon oil. The hydrocarbon oil, say gasoline recovered by centrifuging this emulsion is generally of inferior quality and cannot be added, after its recovery from the emulsion, to the main body of the sweetened gasoline without seriously degrading the latter. I have found that by reforming this recovered gasoline according to the details hereinbefore set forth, that I may improve the quality of this gasoline so that it may be added to the main body of the sweetened gasoline without causing degradation of the latter.

Good yields of improved gasoline or naphtha may be recovered from the aforesaid emulsion.

While I have illustrated my invention by means of the foregoing specific example describing a thermal reforming operation, it is pointed out that any of the known reforming catalysts may be employed; or, in other words, that the reforming operation may be carried out catalytically, using as a catalyst say 10% by weight of molybdenum oxide and activated alumina.

Hydrogen may also be employed, say 10 to 90 mol per cent.

The term reforming" as employed herein means the heat treatment of naphthas for the purpose of improving the octane number thereof without materially changing the boiling range of said naphthas.

Many modifications falling within the spirit of my invention may be made by those familiar with this art.

What I claim is:

1. An improved process for the preparation of sweet high octane gasoline which comprises treating sour gasoline with aqueous sodium plumbite, thence adding sulfur, whereby two liquid phases consisting of an upper sweetened gasoline phaseand a lower emulsion phase are formed,

separating the two phases, centrifuging the emulsion phase to recover low grade gasoline therefrom, subjecting said low grade gasoline to a reforming operation at elevated temperatures to recover a product low in sulfur and having a high octane number, and adding the product to said sweetened gasoline.

2. The process set forth in claim 1 in which the reforming operation is carried out at a temperature within the range of from about 900 to 1050 F. I

3. The process set forth in claim 1 in which the reforming operation is performed thermally.

4. The process set forth in claim 1 in which the reforming operation is carried out catalytica 1y.

5. The process specified in claim 1 in which the reforming operation is carried out under superatmospheric pressure 

